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\title{Turtlebot SLAM }
\author{Murtadha Alqurqush\\Cristian Calmuschi\\Andreas Hamacher\\Gergely Kosztolanyi\\Yannick Thimister}
\date{\today}
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\begin{document}

\frame{\titlepage}

\section[Outline]{}
\frame{
\frametitle{Outline}
\tableofcontents}


\section{Introduction}
\frame{
\frametitle{Introduction}
\begin{itemize}
	\item Example: Exploring Rome without a map
	\item Simultaneous Localization and Mapping (SLAM)
	\item Turtlebot platform + Landmark detection
\end{itemize}


}

\subsection{Research Questions}
\frame{
\frametitle{Research Questions}
\begin{itemize}
	\item \textbf{Phase 1:} How to create an efficient and accurate exploration algorithm for a mobile robot?
	\item \textbf{Phase 2:} How to create an as accurate as possible SLAM algorithm that can run in real-time?
	\item \textbf{Phase 3:} How to incorporate the algorithms in a real-world environment using a Turtlebot?
\end{itemize}
}

\section{General structure}

\subsection{Turtlebot and ROS}
\frame{
\frametitle{Turtlebot and ROS}
	\begin{itemize}
		\item Turtlebot
		\begin{itemize}
			\item Mobile robot
			\item Microsoft Kinect
			\item Laser range sensor
		\end{itemize}
		\item Robot Operating System (ROS)
	\end{itemize}
	\begin{figure}
	\begin{picture}(0.5,0.5)(0.5,0.5)
		\includegraphics[width=0.4\textwidth]{turtlebot320.png}
		\end{picture}
		\end{figure}
}

\subsection{Program Structure}
\frame{
\frametitle{Program Structure}
	\includegraphics[width= \paperwidth]{rxgraph.PNG}

}

\section{Exploration}
\frame{
\frametitle{General Exploration}
\begin{itemize}
	\item Good exploration strategy
	\begin{itemize}
		\item Accuracy
		\item Efficiency
	\end{itemize}
	\item Occupancy Grid Map
	\item Frontier-Detection algorithm
	\item Navigation
\end{itemize}
}

\subsection{Occupancy Grid Map}
\frame{
\frametitle{Occupancy Grid Map}
\begin{itemize}
	\item Goal: Estimate the posterior probability over maps given the data $p(m | z, x) $
	\item Map as grid over the continuous space
	\item Each grid contains probability
		
		\center
		\includegraphics[width = 100pt]{occGridMap.png}
\end{itemize}
}

\subsection{Frontier Detection}
\frame{
\frametitle{Frontier-Based Detection}
\begin{itemize}
	\item Frontiers: regions between open space en unexplored space
	\item Create evidence grid
	\item Label frontier cells
	\item Create frontiers
	\item Find centroid
	\item Wavefront detection
\end{itemize}

\footnotetext{\tiny Source: Yamauchi, B (1997). A Frontier-Based Approach for Autonomous Exploration. Navy Center for Applied Research in Artificial Intelligence, Washington.}
}

\frame{
\frametitle{General Idea of Exploration}
\includegraphics[width=0.25\paperwidth]{step1.png}
\hspace{10pt}
\includegraphics[width=0.25\paperwidth]{step2.png}
\hspace{10pt}
\includegraphics[width=0.25\paperwidth]{step3.png}
\begin{itemize}
	\item Left: Initial Localization, Mapping and frontier detection
	\item Middle: Exploration by navigating to a selected frontier
	\item Right: Further exploration based on the given strategie
\end{itemize}
}

\subsection{Navigation}
\frame{
\frametitle{Navigation}
\begin{itemize}
	\item Two possible approaches
	\begin{itemize}
		\item Topological aproach based on connected regions
		\item Grid-based approach based on occupancy grid
	\end{itemize}
	\item Currently testing topological
\end{itemize}
}

\section{SLAM}
\frame{
\frametitle{SLAM}
\begin{itemize}
	\item Sensor data perceive landmarks and walls
	\item Odometry data provides estimate of the robot's position
	\item Main part is an Extended Kalman Filter
	\begin{itemize}
			\item Update belief based on observations of features/landmarks
			\item Landmarks are features in the environment that are distinguishable
			\item Only re-observed landmarks are used to update
	\end{itemize}

\end{itemize}
}



\section{Planned Experiments}
\frame{
\frametitle{Planned Experiments}
\begin{itemize}
	\item Efficiency
	\begin{itemize}
		\item How long does it take to explore the entire map or \\ when is the last frontier explored
		\item Comparing Strategies on fontier selection. \\ Distance vs. knowledge gain
	\end{itemize}
	\item Accuracy
	\begin{itemize}
	    \item Increase of accuracy vs. measurement time.
		\item How accurate is the found map in comparison to the real map?
		\item Evaluation by visual comparison.
	\end{itemize}
\end{itemize}
}

\section{Future Work}
\frame{
\frametitle{Planning phase 2, Graph Based Slam}
\begin{itemize}		
% based on http://ais.informatik.uni-freiburg.de/teaching/ws10/praktikum/slamtutorial.pdf
% linked on http://eleum.unimaas.nl/webapps/blackboard/content/listContent.jsp?course_id=_13595_1&content_id=_143918_1&mode=reset&courseTocLabel=COURSE_DEFAULT.CourseInformation.CONTENT_LINK.label
		\item Localization
        \begin{itemize}
        	\item Extended Kalman Filter
		\end{itemize}
		\item Mapping functionality
        \begin{itemize}
        	\item Visualization
        	\item Graph datastructures and interface
		\end{itemize}	
        \item Graph construction (front end)        
        \begin{itemize}
        	\item scan matching 
        	\item loop detection
		\end{itemize}
        \item Graph optimization (back end)
        \begin{itemize}
        	\item Numerics - multimodal minimization problem
		\end{itemize}
		\item General
		\begin{itemize}
        	\item Solve chicken egg dilemma
        	\item Testing and debugging Environment
		\end{itemize}
	
\end{itemize}
\footnotetext{\tiny Source: Giorgio Grisetti Rainer Kummerle Cyrill Stachniss Wolfram Burgard. A Tutorial on Graph-Based SLAM}
}

\frame{
\frametitle{Planning phase 2, Gantt}
\includegraphics[width=0.95\paperwidth]{gantt_phase2.png}
}

\section{Questions}
\frame{
\frametitle{Thanks and Questions?}
\begin{itemize}
	\item Thank you for your attention
	\item Questions?
\end{itemize}
}

\frame{
\frametitle{Questions}
\begin{itemize}
	\item Please give feedback on the planning
	\item Hint on debugging of graph construction and optimization
	\item Literature on evaluation of mapping accuracy
\end{itemize}
}


\frame{
\frametitle{Example}

\includegraphics[width=\paperwidth]{frontierdetection.png}
}
\end{document}